The invention relates to novel uses of an okume resin extract, in the cosmetic and pharmaceutical fields, and in particular in the dermatological field.
More precisely, the invention relates to uses as a cosmetic agent of an okume resin extract, more particularly for care of the skin, the nails, and the hair.
The invention also relates to certain uses in the field of pharmacy.
xe2x80x9cOkumexe2x80x9d and xe2x80x9cGaboon mahoganyxe2x80x9d are common names corresponding to the plant Aucoumea klaineana which is the only species of the genus Aucoumea of the family Burseraceae.
The okume is a tall tree of the equatorial rain forests of West and Central Africa. It is used for its wood and constitutes the majority of the wood exported by Gabon.
Its young branches are covered in rust-red down. Its leaves are alternate, imparipinnate, and with elongate oval leaflets, and they are glabrous and shiny. Young leaves are a bright red color; they appear starting in October to December-January, giving the tree tops a reddish color, which makes it possible to identify okume populations from the air.
The inflorescences are in 10 cm to 20 cm long panicles, with whitish flowers that are practically odorless. Flowering takes place in October-November.
The fruit are capsular and glabrous; they open into five leathery lobes. The seeds are triangular, and extended by a blade-shaped wing. Fruiting is towards the month of February.
The color of the bark varies from purplish red to salmon pink depending on the age of the plant. The bark is lightly fibrous, almost granulous, and when cut it oozes out a resin or oleoresin that smells strongly of turpentine and that becomes opaque on coagulating.
The resin essentially contains monoterpenes and triterpenes with a backbone of olenane and tirucallane.
Traditional uses are known for this resin: originally okume resin was used in Gabon to make torches used during initiation ceremonies. That use which persists to the present day in villages, is extended in towns during family gatherings. In missionary stations, it is used as a substitute for incense. In folk medicine, it is used to bring abscesses to a head and in the treatment of wounds where it activates healing.
Pharmacologically, the oleoresin has antibacterial power, due in particular to phenols contained in essential oil.
For further details on the uses and properties of okume or its oleoresin, reference can be made to the following publications:
Tessier A. M., Delaveau P., Piffault N., Hoffelt J., Planta Med. 46, 41 (1982);
Delaveau P., Lallouette P., Tessier A. M., Planta Med., 40, 49 (1980);
Delaveau P., Vidal-Tessier A. M., Bull. Soc. Bot. Fr., 135, Actualitxc3xa9s bot., 3, 25 (1988).
Systemic testing carried out by the inventors has revealed a certain number of surprising enzymatic actions of this resin, in particular inhibiting action on various enzymes, in particular keratinase, elastase, phospholipase A2, and lipoxygenase, which makes it possible to envisage using it in cosmetics, in particular in substances for care of the skin, the nails, and the hair.
Keratinase is an enzyme produced on the body essentially by fungi. It is produced industrially from Streptomyces fradiae. Its action on the skin, and on the integuments leads to degradation of keratins, which gives rise in particular to disorganization in the structure of the integuments (white or striped nails, brittle hair, etc.).
Elastase, the enzyme for degrading elastin, is present in cells, in particular in dermal cells (fibroblasts) and also, to a lesser extent, in epidermal cells (keratinocytes). It has been observed that the quantity and the activity of elastase increases during the process of skin aging, whether the aging is intrinsic or actinic. By degrading elastin fibers, the action of elastase causes a loss of cutaneous elasticity, a slackening of the skin, and the appearance of wrinkles.
Phospholipase A2 (PLA2) is an enzyme produced by membrane cells. It predominates in cells associated with inflammatory phenomena, such as mast cells. Its action is to release arachidonic acid bonded to the phospholipids of the membrane. This acid then metabolizes into various lipid mediators of inflammation and allergy, such as leukotrienes and prostaglandins.
5xe2x80x2-lipoxygenase, referred to below as xe2x80x9clipoxygenasexe2x80x9d is, like PLA2, a membrane enzyme. It is involved in the xe2x80x9cinflammation cascadexe2x80x9d downstream from the release of arachidonic acid by PLA2, in converting the acid into leukotrienes, mediators of inflammation.
The inventors have thus shown that because of their inhibiting action on the above-mentioned enzymes, extracts of okume resin are most advantageous in cosmetics and in therapy.
More particularly, the invention provides compositions for care of the nails, the hair, and the eyelashes, in combatting the effects of skin aging, and in preventing or treating cutaneous inflammations and allergies.
By the discovery that okume resin extracts are active in inhibiting the action of enzymes, the invention provides various solutions in the field of cosmetics and therapy, and in particular in the field of dermatology. By inhibiting keratinase, the compositions of the invention serve to prevent and treat deterioration of keratin structures, in particular in the integuments, the nails, the hair, and eyelashes. By inhibiting elastase, the compositions of the invention oppose degradation of elastin fibers, and as a result such compositions maintain the biomechanical qualities of the skin, and in particular its qualities of elasticity in the dermis, thus combatting slackening of the skin and the appearance of wrinkles. By inhibiting phospholipase A2 and lipoxygenase, compositions of the invention thus have two actions in limiting or blocking the process of forming cutaneous allergy mediators and inflammation mediators.
In another advantage of the invention, okume resin turns out to be soluble in numerous organic solvents. It is even almost completely soluble in esters such as ethyl acetate and butyl acetate, thus making it all the more advantageous in the manufacture of nail varnish, which generally makes use of these solvents, in particular in the manufacture of treatment nail varnish.
Another advantage of using okume resin extracts in treatments for the nails, in particular in nail varnishes, stems from the fact that these extracts themselves have film-forming characteristics when applied on a surface, in particular the surface of a nail.
These film-forming qualities of okume resin can also be used to advantage in compositions for application to the hair or to the eyelashes, in particular in compositions for hair dressing such as lacquers, gels, or emulsions, or indeed in mascara compositions for improving the coating of eyelashes.
Other advantages of the invention appear from the following description and examples.
Thus, according to one of its essential characteristics, the invention relates to cosmetic compositions containing an okume resin extract in the presence of a cosmetically acceptable vehicle.
The extract is advantageously obtained by macerating the resin in a solvent of medium or weak polarity, followed by filtering the mixture. The solvent of the resulting solution can be evaporated where necessary in order to obtain a dry extract.
A solvent of xe2x80x9cmedium or weak polarityxe2x80x9d means a solvent whose polarity parameter is less than or equal to 6, where this index is defined in Practical high-performance liquid chromatography by Meyer V. R., 1988, pp. 120-121.
Evaporation is preferably performed under low pressure.
Solvents that can be used advantageously include the following:
C6 to C12 aliphatic hydrocarbons such as hexane and heptane;
chlorine-containing solvents, in particular dichloromethane;
ethers such as ethyl ether or diisopropyl ether;
acetone;
esters such as ethyl acetate and butyl acetate; and
C1 to C4 alcohols, such as methanol, ethanol, and isopropanol.
Okume resin extract can also be obtained by the so-called supercritical carbon dioxide extraction technique.
Extraction yield depends essentially on the age of the tree.
Thus, by using ethyl acetate as the solvent, extraction yield lies in the range 90% to 98% depending on the age of the tree.
In an advantageous embodiment, the composition comprises 0.01% to 10% by weight and in particular 0.2% to 1% by weight dry extract of okume resin relative to the total weight of the final composition.
In other advantageous embodiments of the invention, the composition is formulated for topical application to the skin, to the hair, to the eyelashes, or to the nails.
Tests performed by the inventors have also clearly shown that not only is extraction yield tied to the nature of the solvent used, but so also is the enzymatic activity of the extract. The accompanying examples show clearly the effect of solvent selection on the enzymatic activity of the extract.
The quantity of extract is also selected as a function of the desired film-forming effect. A particular advantage associated with the nature of the substance enables the extract to confer film-forming qualities to the composition, or to improve them.
Compositions of the invention can be formulated in any form that is accepted for their use in cosmetics. In particular, the composition can be a cream, in particular a cream for the face or the hands, a gel, in particular a hair gel, a balm, in particular untangling balm, a mascara, a foundation, or a preparation for the nails, such as a treatment base or a treatment nail varnish.
In another aspect, the invention concerns the use of okume resin as a cosmetic agent, said agent being incorporated in a cosmetic composition as defined above.
The quantity of this agent can be adapted as a function in particular of the film-forming qualities desired of the composition.
Cosmetic compositions of the invention are used in any field associated with care or makeup.
In particular, the cosmetic agent can be used in all applications where it is desired to inhibit the action of keratinase and/or elastase and/or phospholipase A2 and/or lipoxygenase.
Such compositions are intended in particular for care of the nails, the hair, or the eyelashes, in particular for keeping them in good condition as to keratin structure, so as to facilitate hair dressing or to improve eyelash makeup.
Such compositions are also used to combat the effects of skin aging, in particular by preserving or improving the biomechanical qualities of the skin, in particular its elasticity, by delaying the appearance of wrinkles, or by reducing wrinkle depth and improving cutaneous firmness.
Such compositions are also used for combatting the harmful effects of free radicals on the skin, for care or makeup of sensitive skins, in particular by attenuating or eliminating phenomena of irritation, inflammation, or allergy that generally give rise on the skin to red patches, or to burning or tingling sensations.
Thus, cosmetic compositions of the invention are used in particular for any cosmetic application where it is desired to inhibit the activity of the above-mentioned enzymes.
This is the case in particular of compositions for care of the hair, the eyelashes, or the nails, where said antikeratinase activity is particularly desired.
Thus, in another aspect, the invention relates to cosmetic compositions for care of the skin, in particular to combat inflammation or cutaneous aging.
In yet another aspect of the invention, it provides cosmetic compositions for hair care. In particular, they can be hair lacquers, gels, or emulsions.
The invention also provides makeup, in particular treatment makeup such as nail varnishes, mascaras, or foundations.
In a particularly advantageous aspect of the invention, it also relates to cosmetic compositions for treatment of the nails. Keratin, a structural protein, is predominant in nails and imparts rigidity thereto. With aging, keratins become less rigid, so nails become softer, more breakable, and also more vulnerable to attack from various proteases such as keratinase. Compositions of the invention can thus advantageously be used for nail care, in particular because of their keratinase inhibition action as demonstrated by tests performed by the inventors.
In addition to its properties of inhibiting keratinase and its quasi-total solubility in the solvents used for preparing nail varnishes, okume resin has the advantage of improving the film-forming character of such compositions, thus greatly contributing to the Theological properties and qualities of such varnishes after they have been applied to the nails.
As mentioned above, the effectiveness of the above-described cosmetic compositions has been correlated with various kinds of enzymatic activity. The demonstration of this enzymatic activity makes it possible also to envisage using the above-defined extracts for preparing pharmaceutical compositions, in particular dermatological compositions in which these kinds of activity are desired. Tests performed by the inventors of the present invention have confirmed the effectiveness of such pharmaceutical compositions.
Thus, phospholipase A2 inhibition and 5xe2x80x2-lipoxygenase inhibition have been correlated with effectiveness in preventing and treating inflammation phenomena.
In addition, keratinase inhibition activity has been correlated with activity in the field of treating complaints affecting keratin, in particular in the nails, the eyelashes, and the hair.
Thus, according to another essential characteristic, the invention also provides the use of an okume resin extract in preparing a pharmaceutical composition, in particular a dermatological composition, for preventing or treating complaints of the integuments, in particular the nails, giving rise to deterioration of keratin structures, such as onychomycoses, for treating the effects of intrinsic or actinic aging of the skin, for treating the harmful effects of free radicals on the skin, for preventing or treating cutaneous manifestations of allergies and inflammations, said extract being incorporated in a pharmaceutically acceptable vehicle.
The invention also relates to methods of therapeutic and in particular dermatological treatment, for preventing or treating complaints of the integuments, in particular the nails, giving rise to deterioration of keratin structures, such as onychomycoses, for treating the effects of intrinsic or actinic aging of the skin, for treating the harmful effects of free radicals on the skin, for preventing or treating cutaneous manifestations of allergies and inflammations, in which an effective quantity of a pharmaceutical composition containing an okume resin extract is applied to the part of the body to be treated.
For these various applications, the pharmaceutical composition advantageously presents inhibitory activity on keratinase and/or elastase and/or phospholipase A2 and/or lipoxygenase.
In a variant, the invention relates to using an okume resin extract for preparing a pharmaceutical composition, in particular a dermatological composition, for treating and preventing manifestations of allergies, in particular cutaneous allergy or the treatment of the harmful effects of free radicals.
These two types of application are directly associated with inhibiting the lipid mediators of inflammation.
In these applications in the pharmaceutical field, in particular in the dermatological field, the compositions used are preferably compositions for topical application designed to be applied in particular to the skin and the integuments. The okume resin extracts used for preparing them are obtained in the same manner as the extracts used in the field of cosmetics, and they are introduced into a vehicle that is pharmaceutically and in particularly dermatologically acceptable in concentrations lying in the range 0.01% to 10% by weight, and in particular in the range 0.2% to 1% by weight, of dry extract of said resin.
As in cosmetic applications, the extraction solvent is selected as a function of the type of enzymatic activity that it is desired to favor in the action of the pharmaceutical composition.
Pharmaceutical, and in particular dermatological, compositions of the invention can also contain various pharmacologically active substances usable in the treatment of diseases of the integuments and in particular of the nails.
In particular, such compositions can contain agents known for their antifungal activity, in particular agents that are active on the dermatophytes that are responsible in particular for onychomycoses.
Amongst these agents, particular mention can be made of the ethanolamine salt of ciclopirox, also known as ciclopirox olamine.